1. Field of the Invention:
The invention relates to portable optical scanners for reading indicia of varying light intensity, and in particular to such scanners which are adapted to be worn on the person.
2. Description of the Related Art
Various optical readers and optical scanning systems have been developed heretofore for reading indicia such as bar code symbols appearing on-the label or on the surface of an article. The symbol itself is a coded pattern of indicia comprised of, for example, a series of bars of various widths spaced apart from one another to bound spaces of various widths, the bars and spaces having different light reflecting characteristics. The readers in scanning systems electro-optically transform the graphic indicia into electrical signals, which are decoded into alphanumeric characters that are intended to be descriptive of the article or some characteristic thereof. Such characteristics are typically represented in digital form and utilized as an input to a data processing system for applications in point-of-sale processing, inventory control and the like. Scanning systems of this general type have been disclosed, for example, in U.S. Pat. Nos. 4,251,798; 4,369,361; 4,387,297; 4,409,470; 4,760,248; 4,896,026, all of which have been assigned to the same assignee as the instant application. As disclosed in the above patents, one embodiment of such scanning systems includes, inter alia, a hand held, portable laser scanning device supported by a user, which is configured to allow the user to aim the scanning head of the device, and more particularly, a light beam, at a targeted symbol to be read.
Such prior art hand held devices generally incorporate a light-receiving module which receives the light that has been reflected from the bar code symbol and determines, from the reflected pattern, the sequences of bars and spaces within the symbol. The unit may also incorporate decoding circuitry to decode the received information and to recover the underlying data (for example the alphanumeric data) which the bar code symbol represents.
It has previously been proposed to provide a small portable scanner attached to a ring which is worn on a finger of the user. To operate the scanner, the user merely points the appropriate finger in the direction required so that the scanning beam scans across the indicia to be read. One difficulty with such an arrangement is that where the operator is engaged in a variety of tasks, only one of which is the scanning of bar codes, it may be inconvenient for the ring repeatedly to have to be put on and taken off again. Also, if the user accidentally knocks the scanner module, or twists it, the ring and/or module might be damaged.